The milestone comes about six years after Sherpa immigrated to the U.S. to join relatives here and escape the tense political landscape of his native country, which had been embroiled in a bloody civil war.

When he arrived in the U.S., Sherpa researched how to become an American citizen and later started the application process.

"I have a better knowledge of the country now," he said, noting that he had to study American history and politics in order to pass the citizenship test.

Sherpa now works as a plumber -- a big change from his past careers as a Sherpa guide in the Himalayas and as a news reporter for Nepal Television.

But he said the change is worth it to gain American citizenship -- a status that will allow him to travel more easily and to finally reunite with his wife, who still lives in Nepal.

He said he also hopes to use his extensive climbing background to open a travel business that would bring mountain climbers to the Himalayas.

"Becoming an American citizen is a great opportunity," he said. "I'm excited."